Instrument current transformer



Feb. 24, 1948 F. R. DENTREMONT 2,436,636

INSTRUMENT CURRENT TRANSFORMER Filed July 14, 1944 (2 Sheets-Sheet l Hls Attorney.

Feb. 24, 1948. DENTREMONT $436,636

INSTRUMENT CURRENT TRANSFORMER Filed July 14, @944 2 Sheets-Sheet 2 ,28 I 1 PIE 9 I: ll Z I II \/V:

V: S I I Ifiventor:

T Franklin R. D Entremont,

Hus Attovney.

Patented Feb. 24, 1948 UNITED STATES PATENT OFFICE INSTRUMENT CURRENT TRANSFORMER Franklin 8. DEntremont, Lynn, Mass., assignor to General Electric Company, acorporation of New York Application July 14, 1944, Serial No. 544,985

I 'an electromagnetic induction apparatus.

Further objects and advantages of my invention will become apparent from the following description referrin to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing Fig. 1 is a side view in partial section illustrating a transformer which is provided with an embodiment of my invention; Fig. 2 is an end view of the structure of Fig. 1; Fig. 3 is an exploded perspective view of the core clamp and supporting structure of the transformer of Figs. 1 and 2; Fig.- 4 is a perspective view partly broken away illustrating the primary winding which is used with the structure .of Figs. 1 and 2; Fig. 5 is an end view of a transformer which is provided with a modification of-my core clamp and supporting structure; Fig. 6 is a side view of the structure of Fig. 5; Fig. 7 is a sectional side elevation of the construction illustrated in Figs. 5 and 6 taken along the line T- l of Fig. 5; Fig. 8 is a perspective view of the cradle clamp employed in the transformer of Figs. 5 and 6, and Fig. 9 is a modification of the invention of Flgaltoi.

Referring more particularly to Fig. 1 of the drawing I have illustrated an electromagnetic induction apparatus such as a transformer having a core member I which is formed in any suitable manner such as by winding a strip of magnetic material into, a generally toroidally shaped core member. Surrounding the core member is an insulated secondary winding 2. Since thetransformer illustrated inFigs. 1 and 2 has particular application as an instrument current transformer the primary winding is pro-- vided by a single bar member 3 illustrated in detail in Fig. 4, which extends through an opening in the core member I. In order to suitably insulate the highand low voltage winding a tubular shaped insulating member 4 is provided around the primar bar 8 and insulation 5 of 6 Claims. (01. 175-358) any suitable. material, such as paper, is built up around the bar on the portions which extend on either side of the insulated secondary winding 2,'such insulation 5 provides a relatively high creepage path between the terminal end 6 of the primary winding bar and the insulated secondary winding 2.

In order to provide an improved arrangement for clamping the core as well as providing a supporting base for the apparatus I provide a core clamp construction which includes a member 1 formed of any suitable material such as metal which surrounds the outer surface of the core I and follows closely the contour thereof. It will be understood that suitable insulation 8 is provided between the core clamp member I and the insulated secondary winding 2. Such insulation will position the core clamp member I as well as insulate the secondary winding 2 from the core clamp member I and the core I. In order to bind the core clamp member I to the outer surface of the core a bolt 9 is provided which extends through apertures [0 in arm members II which are integral with and extend from the core clampmember I. It will be understood thatwhen the nut I2 is tightened on the end of the bolt 2 the core clamp member I will tightly surround the outer surface of the core member. A sleeve I3 is provided around the bolt and between the arms ll so as to prevent the arms from being forced out of shape when the bolt 9' and nut l2 are tightened. A plate It is also provided which is attached to feet members l5 whlchare integral with and extend in substantially right angles with the arms I l, and the plate It and feet l5 may be provided with suitable holes so thatthe apparatus may be suitably attached to any other apparatus.

In Figs. 5 through 8 I have illustrated a modifled type of cradle clamp construction which is employed with a similar core member I. The cradle clamp being provided with arms l8 and I! which are adjacent the outer surface of a portion of the core and follow the contour thereof, as is illustrated in Fig, 5. Feet members l8 and 18 are provided which are integral with the arms l8 and I] so as to provide a space for supporting the apparatus.

As will be seen more particularly in Fig. '7, insulation in the form of flat washers 20 and 2| are provided around the edges of the core and a filler strip of suitable insulating material 22 is provided for surrounding the remainder of the core surface which is not surrounded by the cradle arms I! and I1. Another insulating strip The core clamp and supporting construction described above may be employed with any suitable type of core construction, and in Fig. 9 I have illustrated my invention as applied to a generally toroidally shaped core 28 which isformed by fiatwise curved strips of magnetic material. Surrounding the outer surface of the core there is provided a core clamp construction 29 which is similar to that illustrated in Fig. 3, except that it is more generally rectangular in shape so as to suitably -fit the outer surface of the generally rectangularly shaped core 28. Surrounding the core member there is provided a suitable number of turns providing a secondary winding 30. A bolt 3| is placed between the outwardly extending arms 32 of the core clamp construction 29 for relatively tightly binding the core clamp around the core.

It will be seen that in the construction illustrated in the drawing and described above, I have provided a cradle clamp construction for supporting the core as well as providing a base or supporting structure for the apparatus.

Although I have shown and described particular embodiments of my invention, I do not desire to be limited to theparticular embodiments described, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

'1. An electromagnetic induction apparatus including a toroidally shaped core formed of a fiatwise curved strip of magnetic material, core clamp means including a metallic member embracing the outer periphery of said core, a winding around said core and clamp, insulating means between said core clamp and said winding for positioning said clamp on said core and for insulating said clamp and core from said winding, and means integral with said core clamp for providing asupporting base for said apparatus.

2. An electromagnetic induction apparatus including a toroidally shaped core, cradle core clamp means including two arms adjacent and having the same general contour as the outer surface of said core, a winding surrounding said core and core clamp, said core clamp having integral feet for providing a base for said apparatus.-

3. An electromagnetic induction apparatus including a toroidally shaped core, a winding on said core, core clamp means including a member surrounding the outer periphery of said core inside said winding, means for binding said core clamp member relatively tightly around the outer periphery of said core, and means including integral feet extending from said core clamp member for providing a supporting base for said apparatus.

4. An electromagnetic induction apparatus including a closed core, a winding on said core, core clamp means including a member surrounding the outer periphery of said core under said winding, means for binding said core clamp member relatively tightly around the outer periphery of said core, and means including feet extending from said core clamp for providing a supporting base for said apparatus.

5. An electromagnetic induction apparatus including a closed laminated core having radially superposed layers of flatwise curved magnetic strip material, a core clamp having means which closely embraces a substantial part of the outer periphery of said core, integral feet members on said clamp for providing a supporting base for said apparatus, and an insulated electrical winding wrapped around both said core and clamp except where said feet extend away from said clamp.

6. In combination, a ring-shaped magnetic core of radial superposed lamination layers, a core clamping band surrounding the outer lamination layer, a winding around said core and clamping band, and means including feet extending from said clamping band for providing a base for said core and winding.

FRANKLIN R. DENTREMON'I.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 755,800 Schmidt Mar. 29, 1904 1,130,260 Dann Mar. 2, 1915 1,586,889 Elmen June 1, 1926 2,162,496 Wentz June 13, 1939 2,297,606 Camilli Sept. 29, 1942 FOREIGN PATENTS Number Country Date 539,093 Great Britain Aug. 27, 1941 

